U.S. patent application number 12/626348 was filed with the patent office on 2011-05-26 for method for removing gases from a container having a powdered concentrate for use in hemodialysis.
This patent application is currently assigned to Fresenius Medical Care Holdings, Inc.. Invention is credited to Roland Levin, Wayne Raiford.
Application Number | 20110120946 12/626348 |
Document ID | / |
Family ID | 44061332 |
Filed Date | 2011-05-26 |
United States Patent
Application |
20110120946 |
Kind Code |
A1 |
Levin; Roland ; et
al. |
May 26, 2011 |
METHOD FOR REMOVING GASES FROM A CONTAINER HAVING A POWDERED
CONCENTRATE FOR USE IN HEMODIALYSIS
Abstract
An apparatus and a method for filling a container containing a
dry powdered salt concentrate for use in dialysis with purified
fluid and removing the trapped air or gases generated during the
filling of the container, while maintaining the required fluid
level in the container and without the need for evacuating gases
from the container prior to filling.
Inventors: |
Levin; Roland; (San Ramon,
CA) ; Raiford; Wayne; (Fairfield, CA) |
Assignee: |
Fresenius Medical Care Holdings,
Inc.
Waltham
MA
|
Family ID: |
44061332 |
Appl. No.: |
12/626348 |
Filed: |
November 25, 2009 |
Current U.S.
Class: |
210/637 ;
210/120; 210/133 |
Current CPC
Class: |
A61M 1/1666 20140204;
A61M 1/167 20140204; A61M 1/1658 20130101 |
Class at
Publication: |
210/637 ;
210/133; 210/120 |
International
Class: |
B01D 61/26 20060101
B01D061/26; B01D 61/32 20060101 B01D061/32 |
Claims
1. In a system for use with a dialysis apparatus, a method for
removing gases from a container having an inlet and an outlet, and
containing a powdered salt concentrate, the method comprising the
steps of: advancing fluid into the container through the inlet
until a first pressure is reached to create a solution of fluid and
salt concentrate; adding fluid into the container and flushing the
solution through the outlet while maintaining the first pressure
for a period of time to force gases trapped in the container
through the outlet with the solution; and reducing the pressure in
the container to a second pressure.
2. The method of claim 1 wherein the advancing step includes the
step of using an inlet pump to advance fluid into the
container.
3. The method of claim 1 further including monitoring the solution
for the presence of gases.
4. The method of claim 3 further including comparing a monitored
level of gas in the solution to a preset level.
5. The method of claim 3 wherein the reducing step includes
reducing the pressure in the container to a second pressure when a
monitored level of gas in the solution reaches an acceptable
level.
6. The method of claim 1 further including the step of directing
the solution to a drain.
7. The method of claim 1 wherein the powdered salt concentrate
includes at least one of sodium bicarbonate and sodium acetate.
8. The method of claim 1 wherein the step of adding fluid, flushing
the solution, and maintaining the first pressure includes
maintaining the first pressure in the container at a level between
about 0.5 and 5 times the second pressure.
9. The method of claim 1 wherein step of adding fluid, flushing the
solution, and maintaining the first pressure includes maintaining
the first pressure in the container at a level of about 2 times the
second pressure.
10. The method of claim 1 further including the step of monitoring
the pressure in the container with a pressure transducer.
11. The method of claim 1 further including the step of monitoring
the pressure in the container with a pressure transducer located
between a fluid source and the inlet to the container.
12. The method of claim 1 wherein the step of adding fluid,
flushing the solution, and maintaining the first pressure includes
withdrawing the solution via an outlet pump.
13. A system for use in a dialysis apparatus, the system
comprising: a fluid source; at least one line adapted to allow the
passage of fluid, the hydraulic line having a first end in fluid
communication with the fluid source and a second end in fluid
communication with a drain; an inlet pump disposed along the
hydraulic line and in fluid communication with the fluid source; a
container containing a powdered salt concentrate, the container
having an inlet and an outlet, the inlet being adapted to receive
fluid from the inlet pump, and the outlet adapted to pass a
solution of the fluid and the salt concentrate; a valve disposed
downstream from the inlet pump and in fluid communication with the
hydraulic line, the valve being disposed to selectively divert
fluid flow from the hydraulic line to the inlet of the container; a
pressure sensor disposed to monitor pressure in the container; the
outlet of the container in fluid communication with the hydraulic
line downstream from the bypass valve; and a controller adapted to
control operation of at least one of the inlet pump and the valve
in response to pressure data provided from the pressure sensor.
14. The system of claim 13 further comprising an air sensor
disposed to detect gases in the solution, the controller being
adapted to control operation of at least one of the inlet pump and
the valve in response to solution gas data from the air sensor.
15. The system of claim 13 further comprising an outlet pump
located downstream from the outlet of the container and in fluid
communication with the hydraulic line.
16. The system of claim 13 further comprising second valve
downstream the container.
17. The system of claim 13 further comprising an air separation
chamber having an inlet, an outlet, wherein the inlet of the air
separation chamber is in fluid communication with the outlet of the
container and the outlet of the air separation chamber is in fluid
communication with the hydraulic line downstream from the bypass
valve.
18. The system of claim 17 further comprising an outlet pump
located downstream from the outlet of the container and in fluid
communication with the hydraulic line, wherein the outlet pump is
in fluid connection with the outlet of the air separation
chamber.
19. The system of claim 17 wherein the air separation chamber
further comprises a vent, and the system comprises a vent line in
fluid connection with the vent and with the hydraulic line.
20. The system of claim 17 further comprising an air sensor
disposed to detect gases in the solution, the air sensor being in
communication with the air separation chamber, and the controller
being adapted to control operation of at least one of the inlet
pump and the valve in response to solution gas data from the air
sensor.
Description
BACKGROUND OF THE INVENTION
[0001] Dialysis is performed as a treatment for patients suffering
from renal insufficiency. Dialysis can be performed either in the
peritoneum, or through extracorporeal dialysis or filtration of
blood. These two dialysis methods have in common the fact that
dialysis fluids or dialysates take up the degradation products of
metabolism. These dialysates usually contain high levels of sodium
chloride and other electrolytes, such as calcium chloride, or
potassium chloride, a buffer substance, such as bicarbonate, or
acetate and acid to establish a physiological pH, plus optionally,
glucose or another osmotic agent.
[0002] Dialysates are either supplied as ready-to-use solutions or
they are prepared on site from concentrates, including solid
concentrates. Solids offer the advantage of a small package volume
and a low weight. Although solids also have
disadvantages--electrolyte salts, for example, are highly
hygroscopic--there is a trend toward offering only solid components
for preparation of dialysates.
[0003] In the above mentioned hemodialysis systems, a flexible bag
or container filled with a powdered salt concentrate is used to
generate a concentrated salt solution. Purified fluid is added to
the top of the container and the concentrated solution is removed
from the bottom of the container. When the concentrated solution is
removed from the bottom of the bag it is generally delivered to the
hemodialysis machine for use in the dialysate. It is important that
the fluid level in the container with the salt concentrate is
maintained above the level of the salt in the container, when the
solution is being pumped out of the bottom of the container. Under
normal operation, the fluid level above the powdered salt layer is
maintained or increases as the salt concentrate is consumed.
However, if the fluid level falls below the level of the salt
concentrate, air or gases in the bag may be pumped through the salt
concentrate and out of the bottom of the container into the
dialysate.
[0004] During hemodialysis, using systems such as described in U.S.
Pat. No. 5,385,564 and U.S. Pat. No. 5,616,305, incorporated by
reference herein, dry bicarbonate or acid concentrate is mixed with
dialysate via a container using one or more ports. Even when the
container is filled there is always air remaining in the container.
The system cannot remove all of the air from the container without
evacuating the air from the container via a vacuum system to create
negative pressure, before filling the container with fluid.
[0005] To deter air from being drawn into the hydraulics of the
machine during operation, it is desirable to fill the container
with a sufficient volume or fluid to maintain a fluid layer above
the dry powder. In the systems known in the art, without removing
air from the bag via a vacuum, some containers will not maintain
the correct fluid layer, and thus, extra air passes into the
hydraulics which requires excessive venting procedures. The new
method and arrangement of the present invention solves the problem
without the need to generate a vacuum to evacuate the gases from
the concentrate.
BRIEF SUMMARY OF THE INVENTION
[0006] In an embodiment, the present invention provides a system
and a method for filling a container containing a dry powdered salt
concentrate with purified fluid for use with a dialysis apparatus.
According to a disclosed method, the trapped air or gases generated
during the filling of the container are forced out of the container
without the creating a vacuum in the container prior to
filling.
[0007] According to a disclosed method, fluid is rapidly pumped
into a container having a dry powdered salt concentrate. When the
interior of the container reaches a first pressure, contents of the
container, including residual and generated gases as well as some
fluid, are permitted to flush from the container, and out
eventually out of the system. During this flushing step, adequate
fluid is provided to maintain the first pressure within the
container. At the conclusion of the flushing step, the pressure in
the container is reduced to a second, lower operating pressure, and
the system begins regular operation with delivery of solution to
the dialyzer. According to various embodiments, the flushing step
may proceed for a set time, or until such time a given level of air
is no longer detected in the solution leaving the container for a
given period of time.
[0008] In another embodiment, the present invention also provides a
system for removing gases from a container having a powdered salt
concentrate for use in a dialysis apparatus. The system further
includes a fluid source, a pump which is in fluid communication
with the fluid source, at least one hydraulic line having one end
in fluid communication with the fluid supply and a second end in
fluid communication with a drain. The system further includes a
bypass valve that is disposed downstream from the first pump and
upstream from the inlet of the container. The valve is capable of
directing fluid flow into the hydraulic line or into the container.
An outlet of the container is in fluid communication with the
hydraulic line downstream from the bypass valve. A pressure sensor
monitors the pressure of the fluid pressure in the container.
[0009] In an embodiment, a second valve is provided downstream the
container to facilitate pressurization of the container. In another
embodiment an air sensor is provided to detect gases in the
solution flowing from the container.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0010] FIG. 1 is a schematic diagram the general environment where
the system is operating. A patient is shown attached to a dialysis
apparatus. It is understood that the system of the present
invention supplies dialysate solution to such an apparatus for use
in hemodialysis.
[0011] FIG. 2 is a schematic diagram of an embodiment of a system
for the production and discharge of a liquid hemodialysis
concentrate for use in a dialysis apparatus.
[0012] FIG. 3 is a representative drawing of an embodiment of a
container having a powdered salt concentrate that can be used in
the method and system of the present invention.
[0013] FIG. 4 is a partially cross-sectioned view of an embodiment
of a container having a powdered salt concentrate that can be use
in the method and system of the present invention.
[0014] FIG. 5 is a schematic diagram of an embodiment of a system
for the production and discharge of a liquid hemodialysis
concentrate for use in a dialysis apparatus.
DETAILED DESCRIPTION OF THE INVENTION
[0015] For the purposes of this disclosure, the term "operating
pressure" means the fluid or fluid pressure in the container having
a powdered salt concentrate, during operation of the system, where
the system is capable of supplying a concentrated salt solution to
the dialysis apparatus. The term "flushing step" means operating
the system to remove trapped gases from a container having a
powdered salt concentrate, by pumping fluid through the container
at a pressure that is greater than the operating pressure of the
system, and directing the outflow out of the system to a drain,
instead of to a dialysis apparatus.
[0016] Turning now to the drawings, FIG. 1 displays the general
context of a dialysis system 10. The dialysis system 10 includes
the dialyzer 11, and a subsystem 12 for preparing a salt solution
from a powdered salt concentrate for use in the dialyzer 11. The
salt solution is provided to the dialyzer 11 for administration to
a patient 13. The dialysis system 10 may additionally include
various other optional subsystems and equipment.
[0017] FIG. 2 illustrates a representative hydraulic arrangement of
the dialysis system 10. By way of a general overview of the
operation, the system 10 includes a main hydraulic line 20a-d that
is fluidly coupled to a fluid source 22 at one end, and to the
dialyzer 11 at the other end, with various optional assemblies
disposed along the mainline 20. It is noted that the mainline 20a-d
may include a plurality of hydraulic lines. In the illustrated
embodiment, optional assemblies are disposed along the mainline 20
in addition to the subsystem 12 for preparing a salt solution and
may include a hydroblock 24 and one or more balancing chambers 26,
28. A return line 30a-f from the dialyzer 11 provides return flow
from the dialyzer 11 to a drain 34. As with the mainline, the
return line 30a-f may include a plurality of hydraulic lines.
Subassemblies such as an air separation chamber 36 or a heat
exchanger 38 may be provided along the return line 30. It is noted
that not all elements of the illustrated hydraulic arrangement are
necessary to the structure and operation of the subsystem 12 for
preparing a salt solution from a powdered salt concentrate,
although a general explanation is provided herein in the interest
of completeness.
[0018] Turning now to the specifics of the illustrated hydraulic
arrangement, the fluid source 22 may include any appropriate type
of fluid or fluids. For example, a reverse osmosis fluid (RO fluid)
source may be provided. It will be appreciated that an alternate
fluid may be provided as required by the system 10. While the fluid
referenced in this disclosure will be fluid, it is intended that
the terms "fluid" and "fluid" will encompass other appropriate
fluids for the purposes of the disclosed method and
arrangement.
[0019] Fluid from the fluid source 22 flows through mainline 20a to
the hydroblock 24. In this embodiment, the heat exchanger 38, a
pressure regulator 40, and a control valve 42 are provided along
the mainline 20a between the fluid source 22 and the hydroblock 24.
While the valve 42 controls overall flow to the mainline 20a, the
pressure regulator 40 may control the pressure of the fluid as it
passes through this section of the mainline 20a. The heat exchanger
38 may heat the fluid somewhat with heat from the return spent
fluid, as will be discussed below.
[0020] The illustrated hydroblock 24 is a multichambered unit, the
fluid being heated by a heater 41 in chamber 24b and vented to a
vent 42 in chamber 24c as the fluid flows through the various
chambers 24a-e of the hydroblock 24. The fluid temperature within
the hydroblock 24 may be monitored and/or controlled by a control
thermostat 44. A deaeration pump 46 pumps fluid between the forth
and fifth chambers 24d, 24e of the hydroblock 24 to return the
fluid to the mainline 20b.
[0021] Leaving the hydroblock 24, the mainline 20b bifurcates at a
branch point 50. Valves 52, 54 control the flow of fluid to the
continuing mainline 20c and a subsystem line 56, respectively. If
the valve 54 is closed and valve 52 open, the fluid continues
through the valve 52 to the mainline 20c. If the valve 54 is open
and the valve 52 closed, fluid proceeds through valve 54 to the
subsystem line 56. As with all of the valves in this disclosure,
the valves 52, 54 may be simple shut-off valves, or other
multiposition valves. For example, valves 52, 54 may be replaced by
a single valve that includes positions that arrest flow entirely,
that direct flow to the subsystem line 56, or that direct flow
along the mainline 20c.
[0022] Returning to FIG. 2, the subsystem line 56 connects flow
from the mainline 20b to the subsystem 12 for preparing a salt
solution, as will be explained in greater detail below. After
leaving the subsystem 12, the salt solution is returned to the
mainline 20c at least one of junction 58 or 60. The continuing
mainline 20c directs flow to the balance chambers 26, 28, flow
through the balancing chambers 26, 28 being controlled by a
plurality of valves 62-69. Each of the balancing chambers 26, 28
includes two separate subchambers separated by a flexible membrane,
the significance of which will be discussed below. Flow from the
subsystem 12 flows into the respective balancing chambers 26, 28
through valves 62 and 64, and out from the balancing chambers 26,
28 through valves 66, 68.
[0023] Leaving the balancing chambers 26, 28, the fluid from the
subsystem 12 is directed through mainline 20d. Flows to and from
the dialyzer 11 are controlled by a pair of control valves 70, 72
disposed along the mainline 20d and the return line 30a,
respectively. Thus, fluid from the balancing chambers 26, 28
flowing through mainline 20d moves on to the dialyzer 11 when
dialyzer inlet valve 70 is in the open configuration, and bypass
valve 74 in the bypass line 30b is in the closed position.
[0024] Following usage in the dialyzer 11, spent fluid passes the
control valve 72 to return to the system 10 through return line 30a
and 30c with the bypass valve 74 is in the closed position. To
ensure accurate operation of the balancing chambers 26, 28, as
discussed below, spent fluid passes into the air separation chamber
36. From the air separation chamber 36, separated gases, and
potentially fluid, are passed through return line 30d to the drain
34 by opening shutoff valves 76 and 80. Return fluid, from which
the gases have been separated in the air separation chamber 36, may
be pumped by flow pump 78 through return line 30e to one or both of
the balance chambers 26, 28 through valves 63, 65. Leaving the
balance chambers 26, 28 through valves 67, 69, respectively, the
spent fluid is directed to a heat exchanger 38 and the drain 34 by
way of return line 30f, overall flow to the drain 34 being
controlled by shutoff valve 80. It will be appreciated that the
heated spent fluid passing through the heat exchanger 38 may be
used to heat the fluid flowing from the fluid source 22 to the
hydroblock 24.
[0025] Operation of the balance chambers 26, 28 is known in the
art. Within the balance chambers 26, 28, fresh fluid from the
subsystem 12 passes along one side of the internal membranes, while
spent fluid passes along the other side of the internal membranes.
As will be appreciated by those of skill in the art, this pumping
of spent fluid from line 30e along one side of the membrane with
fresh fluid passing along the other side of the membrane results in
a balanced provision of fluid from and to the dialyzer 11 during
use.
[0026] Returning now to the structure and operation of the
subsystem 12 for preparation of a salt solution, as explained in
detail above, fluid flowing from the mainline 20b from the
hydroblock 24 may be directed to the subsystem 12 by opening the
control valve 54 and closing control valve 52 at adjacent junction
50 to provide flow to the subsystem line 56. To prepare the salt
solution, fluid from the subsystem line 56 enters a container 82,
which contains a powdered salt concentrate. The container 82 may be
of any appropriate design, and may include a so-called bi-bag,
which is a collapsible, replaceable bag that encloses the powdered
salt concentrate. As utilized in this disclosure, the term
"container" 82 will be used to designate any or all of a rigid
container, semiflexible container, or a bi-bag.
[0027] An example of a container 82 in accordance with the
disclosed method is shown in FIG. 3. In this view, a protective
cover has been removed to reveal the components of the container
82. The container 82 may be coupled to the subsystem 12 by any
appropriate arrangement. In the illustrated embodiment, the
container 82 is coupled to the subsystem 12 by a connector 88
having an inlet 90 and an outlet 92. As illustrated, the container
82 contains a dry powdered salt concentrate for use in preparation
of a salt solution of a dialysate mixture.
[0028] FIG. 4 shows a partially cross-sectioned view of a container
82 having a protective cover 94 in place. A connector 88 may be
utilized to couple the container 82 to the system 10. In order to
allow the entry of fluid into and the removal of the salt solution
from the container 82, an inlet 90 and an outlet 92 are provided.
Although the inlet 90 and outlet 92 are shown in an upper portion
of the container 82, the inlet 90 and outlet 92 may be alternately
disposed, so long at the requisite mixing is obtained as provided
by the disclosed method. For example, the inlet may be disposed in
a lower portion of the container 82 to allow the fluid to be
injected upward into the container 82 to encourage agitation to
facilitate mixing.
[0029] In order to allow the mixed salt solution to be withdrawn
from a container 82 that is not completely full, the outlet 92
originates below the level of fluid in the container 82. In the
illustrated embodiment, a tube 96 having a lower opening 98 is
fluidly coupled to the outlet 92 such that the opening 98 may be
disposed in a lower portion of the container 82, that is, below the
fluid level. To inhibit the intake of powdered salt that is not yet
dissolved, a filter 100 may be disposed at the opening 98. The
filter 100 may be made of any appropriate material, such as, for
example, porous polyethylene.
[0030] The container 82 and the connector 88 may likewise be made
of any appropriate material, and may be the same as or different
from one another. By way of example only, either or both may be
made of high density polyethylene or similar materials. The
flexible container 82 may likewise be made of any suitable
material, such as, by way of example only, a polyamide-polyethylene
coextruded film.
[0031] The container 82 contains a dry form of one or more of any
suitable salts used for preparation of dialysis solution. By way of
example only, such suitable salts include sodium bicarbonate and
sodium acetate. It will be understood by those of ordinary skill in
the art that, when the powdered salt is sodium bicarbonate in
particular, carbon dioxide will typically be generated from the
initial contact between the fluid and the bicarbonate powder.
Residual air is likewise often disposed within the container 82. As
explained above, in order to provide proper removal of the salt
solution from the container 82, it is necessary to maintain the
opening 98 into the outlet 92 of the container 82 below the surface
of the fluid contained therein. It will thus be appreciated that a
reduction of gases disposed within the container 82 typically
provides more space for the introduction of fluid.
[0032] In order to expel air from the subsystem 12, an air
separation chamber 102 may be provided downstream the container 82.
The air separation chamber 102, which is fluidly connected to the
container 82 by the subsystem line 56, is designed to remove both
air residually disposed within the container 82 and gases
precipitating out of the bicarbonate solution when fluid is
introduced to the powdered salt during operation of the subsystem
12.
[0033] In the illustrated embodiment, an air sensor 114 is provided
on the air separation chamber 102. It will be appreciated that the
air sensor 114 may be alternately disposed and may be of any
appropriate design. For example, the air sensor 114 may be a
two-pronged air detection probe located at the top of the air
separation chamber 102 such that an electric current between the
two prongs is detected when fluid fills the chamber 102 to at least
the level of the prongs. Conversely, when there is air in the
chamber 102, the air between the two prongs acts as an insulator
and electric current does not flow.
[0034] Flow through the air separation chamber 102 is controlled by
a control valve 104. If air is not detected in the air separation
chamber 102, the control valve 104 is closed, the solution proceeds
through subsystem line 108, advanced by a pump 110 to rejoin the
mainline 20c at junction 58. The solution is then passed on to the
balance chambers 26, 28 and to the mainline 20d for delivery to the
dialyzer 11.
[0035] Conversely, if the air sensor 114 detects air in the air
separation chamber 102, the control valve 104 is opened, and air is
vented from the air separation chamber 102 through a degassing line
106 before rejoining the mainline 20c at junction 60. Upon
rejoining the mainline 20c, the gas is passed to the balance
chambers 26, 28 and to mainline 20d; with dialyzer valves 70 and 72
closed, the gas travels through return lines 30b and 30c, through
air separation chamber 36, as explained above, before being
expelled to the drain 34 through line 30d.
[0036] While it is known to withdraw air from the container 82 by
way of a vacuum prior to introduction of fluid to the powdered
salt, the disclosed method does not utilize such a vacuum to remove
all of the gas from the container 82 before the introduction of
fluid, as in the prior art. Rather, the disclosed method provides
the desired layer of fluid over the powdered salt in the container
by minimizing air in the container 82 after the introduction of
fluid thereto. The disclosed method will be explained first with
reference to the basic structure for performing the claimed method
(see FIG. 5), and second with regard to the more detailed
commercial embodiment of the system discussed above (see FIG. 2).
Following these explanations, the operations of the respective
systems by way of a controller are discussed.
[0037] Turning first to FIG. 5, there is illustrated a system 10a
for providing dialysate to a dialyzer 11a. For ease of
understanding, the same reference numerals followed by the letter
"a" are generally utilized to designate similar structures, with
the exception of mainline 20, for which no modifier is
utilized.
[0038] A mainline 20 fluidly couples a fluid source 22a, a
subsystem 12a for the preparation of a salt solution, a drain 34a,
and the dialyzer 11a. The subsystem 12a includes a container 82a
which includes a powdered salt. A pump 46a pumps fluid passing
through a heater and deaerator 24 from the fluid source 22a to
container 82a or to mainline 20c, depending upon which of valves
54a, 52a is open. When valve 54a is open and valve 52a is closed,
fluid is directed to the container 82a. Conversely, when valve 52a
is open and valve 54a is closed, fluid from the pump 46a bypasses
the subsystem 12a entirely.
[0039] According to the disclosed method, with valve 54a open,
valve 104a closed, and pump 110a disabled, the pump 46a pumps fluid
into the container 82a until the pressure within the container 82a
reaches a specified, first pressure level. In the arrangement of
FIG. 5, valve 54a periodically closes to allow a pressure sensor
112a to read the pressure within the line and container 82a. When
the detected pressure reaches the specified, first pressure level,
a flushing step is initiated by opening the downstream valve 104a.
In the flushing step, the salt solution is then pushed from the
container 82a while adequate additional fluid is introduced to the
container 82a to maintain the specified pressure. This rapid
flushing results in the expulsion of both the aqueous salt solution
and gas.
[0040] During the flushing step, the valves 70a, 72a to and from
the dialyzer 11a are closed to isolate the dialyzer 11a from the
remainder of the system 10a. With valve 104a open and valve 52a
closed, the fluid and expelled gas are directed through open bypass
valve 74a to the drain 34a. During this flushing step, the pump 46c
continues to provide fluid to the container 82a to maintain the
pressure in the container 82a at the first pressure level.
[0041] The flushing step continues for either a preset period of
time or until such time as gas is no longer detected in the
expelled fluid, as by an air sensor 114a, for example, for a given
period of time. The required flush time depends upon the volume of
powdered salt disposed within the container 82a, greater amounts of
solution requiring a more lengthy flush time period.
[0042] As discussed above, while the valves of the illustrated
embodiment are simple two position shut off valves, alternate
arrangements are envisioned. By way of example only valves 70a and
74a could be replaced with a three position valve that shuts off
flow entirely, directs flow to the dialyzer, or directs flow to the
drain 34a.
[0043] When the flushing step is completed, the valve 74a is closed
to direct flow to the dialyzer inlet valve 70a as the container 82a
begins normal operation at a second, lower operating pressure.
During normal operation, the container 82a is filled with fluid as
necessary to maintain the lower operating pressure, as the
resultant fluid is directed to the dialyzer 11a.
[0044] The disclosed process of rapidly and immediately pushing
fluid through the bag reduces the amount of gas that vents into the
top of the container 82a, and, instead, pushes the gas out of the
bottom of the container 82a in the flushing step. The expelled gas
includes both residual gases in the container and the powdered
salt, as well as carbon dioxide generated when fluid first makes
contact with the powdered salt. It will be appreciated that the
resultant reduction in gas within the bag provides additional room
for the layer of fluid over the powdered salt.
[0045] The differences between the first pressure, that is, the
flush pressure, and the second pressure, that is, the normal
operation pressure, may be as appropriate to obtain the desired
results. In an embodiment, the pressure in the container 82a during
the flushing step can be raised anywhere from two to five fold over
the operating pressure of the system, depending on the type of
container and system. In an embodiment, the container 82a is
pressurized in range between about 0.5 to 5 times the operating
pressure, preferably between about 1 to 4 times the operating
pressure, more preferably between about 1.5 to 3 times the
operating pressure. In another embodiment, the pressure in the
container 82a is maintained at about 2 times the operating pressure
during the flushing step.
[0046] By way of example only, the fluid and trapped gases may be
flushed from the system for a period of time ranging from 5 seconds
to 5 minutes, depending upon aspects of the arrangement, including,
for example, the volume of the container 82a and the amount of
powdered salt contained therein. In various embodiments, the
flushing step can last anywhere from 10 seconds to 2 minutes, 30
seconds to 2 minutes, 20 to 60 seconds, or about 30 seconds.
[0047] It will be appreciated that the system 10a may include
additional fluid lines and components, such as, by way of example
only, one or more of the components illustrated in FIG. 2 and
explained in more detail above. Referring to FIG. 2, with valve 54
open and valve 52 closed at junction 50, the pump 46 moves fluid
from the fluid source 22 through mainline 20b and subsystem line 56
to the container 82. With valve 104 closed and pump 110 disabled,
pressure rises within the container 82 as fluid continues to be
pumped into the container 82 by pump 46. When the pressure within
the container 82 reaches a preset first pressure level, as measured
by the pressure sensor 112, valve 104 is opened to initiate
flushing of salt solution and gases from the container 82. The salt
solution and entrained gases are then pushed from the container 82
in the flushing step, while the pump 46 provides additional fluid
adequate to maintain the specified pressure within the container
82.
[0048] In the embodiment of FIG. 2, the flushed solution and gas
enter the air separation chamber 102. Upon opening valve 104, the
gas and flushed solution from the air separation chamber 102 flow
through valve 104 and degassing line 106 to junction 60, where it
rejoins the mainline 20c. The gas and flushed solution then proceed
through one or both of valves 62, 64 into one or both of the
balance chambers 26, 28, and out of one or both of valves 66, 68 to
mainline 20d.
[0049] With the dialyzer 11 isolated from the system 10 by closed
input and outlet valves 70, 72, and with bypass line 30b and valve
74 open, the expelled fluids and gas pass through return line 30c
to air separation chamber 36. In air separation chamber 36, while a
portion of the fluid may be separated from the gases, the gases and
potentially fluid are directed through open valve 76 to return line
30d and open valve 80 to the drain 34. During this flushing step,
or during the subsequent recovery step, pump 78 may pump the
separated fluid within the air separation chamber 36 through return
line 30e to one or both of the balance chambers 26, 28 through
valves 63, 65. From the balance chambers 26, 28, the fluid moves
through open valves 67, 69 to an optional heat exchanger 38, on
through open valve 80 to the drain 34.
[0050] In an embodiment, the pressure in the container 82 can range
between about 10 mmHg and 500 mmHg, preferably between about 50
mmHg and 300 mmHg, and more preferably between about 100 mmHg and
200 mmHg. By way of example only, the container 82 may be
maintained at 150 mmHg, while the operating pressure of the
arrangement is on the order of 90 mmHg.
[0051] In order to detect when air is no longer present in the
fluid entering the air separation chamber 36, the air separation
chamber 36 may include an air sensor 116 similar to the air sensor
114 of the air separation chamber 102. Although the air sensors
114, 116 are provided on the air separation chamber 102 and air
separation chamber 36, they may be alternately disposed or
additional sensors may be provided. At the conclusion of a set time
period, or when gas is no longer detected by either one or both of
the air sensors 114, 116, the flushing step may be discontinued,
and the pressure within the container 82 reduced to a regular
system operating pressure, as measured by the pressure sensor 112
or other appropriate sensor.
[0052] During this recovery step, pump 78 may be engaged to pump
any fluids accumulated in the air separation chamber 36 to the
drain. When switching over to regular operation, pump 110 may be
engaged to pump salt solution to join mainline 20c at junction 58,
and the valve 104 may be closed until such time as air is again
detected by the air sensor 114. At this time, the bypass valve 74
is closed to direct flow to the dialyzer 11, and the valves 70, 72
may be reopened as appropriate to direct flow to and from the
dialyzer 11. During regular operation of the system, the pump 46 is
operated to maintain a desired system operating pressure; this
second pressure in the container 82 is lower than the first
pressure utilized in the flushing step of the process.
[0053] During regular operation, the air separation chamber 102
separates gas from fluid in the salt solution progressing to the
dialyzer 11, while the air separation chamber 36 separates gas from
spent fluid returning from the dialyzer 11. It will be appreciated
that this elimination of the gases in the fluids flowing to and
from the dialyzer 11 facilitates efficient and accurate operation
of the balancing chambers 26, 28 during regular operation of the
system 10.
[0054] As with the process explained with regard to FIG. 5, the
disclosed process of rapidly and immediately pushing fluid through
the container 82 in the system 10 of FIG. 2 reduces the amount of
gas that vents into the top of the container 82, and, instead,
pushes the gas out of the outlet 92 of the container 82 in the
flushing process.
[0055] The system 10 may include one or more controllers, which are
capable of activating one or more of the pumps 46, 110, 78, and/or
one or more of the valves 42, 52, 54, 104, 62-70, 72, 74, 76, 80,
and/or receiving input from pressure sensors 112 and/or air sensors
114, 116. For the purposes of this disclosure, we refer to only one
controller, although it will be appreciated that multiple
controllers may be provided. The controller may be of any
appropriate design, such as, for example, a Microchip PIC 18F6410,
although an alternate arrangement may be provided.
[0056] Returning to FIG. 5, the controller 120a receives input from
the pressure and air sensors 112a and 114a, and directs the
actuation/operation of the pumps 46a, 110a and valves 54a, 52a,
104a, 70a, 72a, 74a. In operation, the controller 120 directs the
closure of valves 52a, 70a, 72a, 104a, the opening of valves 54a,
74a, and the disengagement of pump 110a. The controller 120a then
directs the pump 46a to pump fluid from the fluid source 22a to the
container 82a. When the reading received from the pressure sensor
112a reaches a preset first pressure, the controller 120a directs
the opening of the valve 104a, at which time, fluid and gas from
the container 82a is directed through the valves 104a, 74a to the
drain 34a. During this time, the controller 120a directs the
continued operation of the pump 46a at a speed sufficient to
maintain the preset first pressure at pressure sensor 112a. If the
pressure falls below the preset first pressure, the controller 120a
maintain valve 54a in the open position to allow the pump 46a to
continue filling the container 82; conversely, if the pressure is
above the preset first pressure, the controller 120a directs valve
54a to remain closed until such time as the pressure as measured by
the pressure sensor 112a again matches the preset first
pressure.
[0057] When the controller 120a receives a reading of no air from
the air sensor 114a for a set period, the controller 120a causes
the system 10a to operate under regular operation. That is, the
controller 120a directs valves 104a, 74a to close and valves 70a,
72a to open, and directs the engagement of pump 110a to cause the
salt solution to flow to the dialyzer 11a. During regular
operation, the controller 120a maintains a desired second,
operating pressure, as measured by the pressure sensor 112a, the
second, operating pressure being lower than the preset first
pressure. As indicated above, the control of the pressure within
the container 82 may be established by the opening and closing of
valve 54a. In alternate embodiments of the arrangements shown in
both FIGS. 2 and 5, however, control of the pressure within the
container 82 may be established by reductions and increases in the
speed of the pump 46a/46, in conjunction with or separate from the
opening and closing of valve 54a/54 and/or valve 52a/52.
[0058] Referring to the embodiment of FIG. 2, a similar arrangement
may be provided for operation of a controller. In various
embodiments, the controller may receive input from pressure and air
sensors 112, 114, 116, and may direct the operation of any or all
of pumps 46, 110, 78 and any or all of valves 42, 52, 54, 104,
62-70, 72, 74, 76, 80.
[0059] By way of example of one such manner of operation of the
controller, in a first step, the pump 110 is disabled, valves 104,
52 are closed, and valve 54 is opened, and the dialyzer 11 is
isolated by closing valves 70, 72 and opening the bypass valve 74.
In the balance chambers, valves 62 and 65-69 are opened.
[0060] The controller opens valve 54 to allow pump 46 to pump fluid
into the container 82. When the pressure sensor 112 indicates that
the desired, first pressure has been reached, the controller causes
valves 104, 76 and 80 to be opened to flush gas and fluid through
the container outlet through the air separation chamber 102,
through degassing line 106 and mainline 20c, and through the
balance chamber 26 to mainline 20d. The gas and fluid then proceeds
through the bypass line 30b into the air separation chamber 36.
From the air separation chamber 36, the gases proceed through
return line 30d, through valve 80 to the drain 34. During this
flushing step, the controller causes the opening and closing of the
valve 54 in conjunction with the continued operation of the pump 46
to maintain the desired preset first pressure within the container
82 as measured by readings from the pressure sensor 112. After a
preset period of time, for example, thirty seconds, the pump 78 may
be activated to pump any accumulated fluids from the air separation
chamber 36 through return line 30e and balance chamber 28 to the
drain 34.
[0061] Once no air is detected at the air sensor 114 for a period
of time, for example, two consecutive minutes, the controller
causes valve 104 to close. Once the remainder of the fluid and gas
pass through the bypass line 30b, bypass valve 74 is returned to a
closed position, and the remainder of the valves are returned or
set to a regular operating positions. The pump 110 is then
activated, and the controller causes the valve 54 to open and
close, such that the continued operation of the pump 46 provides a
second, lower operating pressure at pressure sensor 112.
[0062] As explained above, the disclosed method may operate to
reduce the residual gases and the gases precipitating from the
solution without drawing a vacuum on the container 82. In the
initial step, pressure is built in the substantially isolated
container 82 until a first preset pressure is obtained. The
flushing step is then initiated to flush gases, fluid, and
entrained gases from the container to a drain. Either after a
preset time or when gas is no longer sensed in the fluid from the
container 82, the system is returned to a second, lower operating
pressure, and the fluid from the container 82 is directed to the
dialyzer 11. In this way, the level of air in the container 82 is
effectively reduced to yield additional space for fluid.
Accordingly, this reduction of air allows for effective operation
of the container 82 in providing a salt solution for dialysis.
[0063] All references, including publications, patent applications,
and patents, cited herein are hereby incorporated by reference to
the same extent as if each reference were individually and
specifically indicated to be incorporated by reference and were set
forth in its entirety herein.
[0064] The use of the terms "a" and "an" and "the" and similar
referents in the context of describing the invention (especially in
the context of the following claims) are to be construed to cover
both the singular and the plural, unless otherwise indicated herein
or clearly contradicted by context. The terms "comprising,"
"having," "including," and "containing" are to be construed as
open-ended terms (i.e., meaning "including, but not limited to,")
unless otherwise noted. Recitation of ranges of values herein are
merely intended to serve as a shorthand method of referring
individually to each separate value falling within the range,
unless otherwise indicated herein, and each separate value is
incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein, is
intended merely to better illuminate the invention and does not
pose a limitation on the scope of the invention unless otherwise
claimed. No language in the specification should be construed as
indicating any non-claimed element as essential to the practice of
the invention.
[0065] Preferred embodiments of this invention are described
herein, including the best mode known to the inventors for carrying
out the invention. Variations of those preferred embodiments may
become apparent to those of ordinary skill in the art upon reading
the foregoing description. The inventors expect skilled artisans to
employ such variations as appropriate, and the inventors intend for
the invention to be practiced otherwise than as specifically
described herein. Accordingly, this invention includes all
modifications and equivalents of the subject matter recited in the
claims appended hereto as permitted by applicable law. Moreover,
any combination of the above-described elements in all possible
variations thereof is encompassed by the invention unless otherwise
indicated herein or otherwise clearly contradicted by context.
* * * * *